pete williams live in d.c. we should note, we've been covering this story all night, since it started at 11:00 at night. we were uncertain throughout the night whether any of these events were linked. it started with reports of a shooting at m.i.t. then it turned to the violence that was taking place at watertown. then while all of this was taking place, we were hearing reports of a carjacking. we were hearing reports of a robbery at a 7-eleven. we didn't know if any of this was related. we didn't know if any of this was related to the boston marathon bombing. throughout the night, we've been trying to ascertain what was what. we wanted to make sure we were very responsible in our reporting and not jump to any conclusions that we didn't have evidence to support. at this time, here's what we can now reasonably conclude. law enforcement officials believe that this all began last night when those two suspects in the boston marathon bombing, the men they released photos of on thursday, those two men you're seeing o